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Chlorellestadite, Ca5(Sio4)1.5(SO4)1.5Cl, a New Ellestadite- Group Mineral from the Shadil-Khokh Volcano, South Ossetia

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Mineralogy and Petrology https://doi.org/10.1007/s00710-018-0571-1 ORIGINAL PAPER Chlorellestadite, Ca5(SiO4)1.5(SO4)1.5Cl, a new ellestadite- group mineral from the Shadil-Khokh volcano, South Ossetia Dorota Środek1 & Irina O. Galuskina1 & Evgeny Galuskin1 & Mateusz Dulski2,3 & Maria Książek4 & Joachim Kusz4 & Viktor Gazeev5 Received: 7 September 2017 /Accepted: 2 April 2018 # The Author(s) 2018 Abstract Chlorellestadite (IMA2017–013), ideally Ca5(SiO4)1.5(SO4)1.5Cl, the Cl-end member of the ellestadite group was discovered in a calcium-silicate xenolith in rhyodacite lava from the Shadil Khokh volcano, Greater Caucasus, South Ossetia. Chlorellestadite forms white, tinged with blue or green, elongate crystals up to 0.2–0.3 mm in length. Associated minerals include spurrite, larnite, chlormayenite, rondorfite, srebrodolskite, jasmundite and oldhamite. The empirical crystal chemical formula of the holotype specimen is Ca4.99Na0.01(SiO4)1.51(SO4)1.46(PO4)0.03(Cl0.61OH0.21F0.11)Σ0.93. Unit-cell parameters of chlorellestadite are: P63/m, a =9.6002(2),c =6.8692(2)Å,V = 548.27(3)Å3, Z = 2. Chlorellestadite has a Mohs hardness of 4–4.5 and a calculated density of 3.091 g/cm3. The cleavage is indistinct, and the mineral shows irregular fracture. The Raman spectrum of chlorellestadite is similar to the spectra of other ellestadite group minerals, with main bands located at 267 cm−1 (Ca–O vibrations), and between −1 4− 2− −1 4− 2− 471 and 630 cm (SiO4 and SO4 bending vibrations) and 850–1150 cm (SiO4 and SO4 stretching modes). Chlorellestadite forms in xenoliths of calcium-silicate composition when they are exposed to Cl-bearing volcanic exhalations at about 1000 °C under low pressure conditions. Keywords Chlorellestadite . New mineral . Crystal structure . Raman . Shadil Khokh volcano . South Ossetia Introduction the Shadil Khokh volcano, Greater Caucasus, South Ossetia. It is a new mineral of the ellestadite group consisting of silicate- Chlorellestadite, ideally Ca5(SiO4)1.5(SO4)1.5Cl, was found in an sulfate apatites (Rouse and Dunn 1982), belonging to the apatite altered calcium-silicate xenolith enclosed in rhyodacite lava from supergroup (Pasero et al. 2010). To date, the ellestadite group has been known to contain only three confirmed minerals: Editorial handling: M. A.T.M. Broekmans – fluorellestadite Ca5(SiO4)1.5(SO4)1.5F, – * Ś hydroxylellestadite Ca5(SiO4)1.5(SO4)1.5(OH), and Dorota rodek – [email protected] mattheddleite Pb5(SiO4)1.5(SO4)1.5Cl. The natural existence of chlorellestadite was long doubted 1 Faculty of Earth Sciences, Department of Geochemistry, Mineralogy and Petrography, University of Silesia, Będzińska 60, mainly due to the lack of credible analyses (Rouse and Dunn 41-200 Sosnowiec, Poland 1982) and its species name was thus proposed discredited 2 Silesian Center for Education and Interdisciplinary Research, (Pasero et al 2010, p. 175) Now, the confirmed Cl-member Institute of Material Science, 75 Pułku Piechoty 1a, of the fluorellestadite-hydroxylellestadite series supplements 41-500 Chorzów, Poland this group. All Ca-members of the ellestadite group have com- 3 Institute of Material Science, University of Silesia, 75 Pułku Piechoty parable optical and physical properties (Table 1), whereas 1a, 41-500 Chorzów, Poland matthedlleite is quite different. 4 Institute of Physics, University of Silesia, Uniwersytecka 4, BChlorellestadite^ was first described from Crestmore, 40-007 Katowice, Poland California, USA (McConnell 1937). Further studies revealed 5 Institute of Geology of Ore Deposits, Petrography, Mineralogy & errors in his crystal chemical formula calculations. As later Geochemistry (IGEM) RAS, Staromonetny 35, assessment has shown that hydroxyl dominates over chlorine 119017 Moscow, Russia D. Środek et al. Table 1 Comparison physical properties of the ellestadite group minerals mineral species Fluorellestadite Hydroxylellestadite Chlorellestadite Mattheddleite (Chesnokov et al. 1987) (Harada et al. 1971) (Livingstone et al. 1987) end-member formula Ca5(SiO4)1.5(SO4)1.5FCa5(SiO4)1.5(SO4)1.5(OH) Ca5(SiO4)1.5(SO4)1.5Cl Pb5(SiO4)1.5(SO4)1.5Cl crystal data P63/m P63/m P63/m P63/m a =9.485(2)Å a =9.496(2)Å a = 9.6002 (2) Å a = 10.0056 (6) Å c =6.916(2)Å c =6.920(2)Å c = 6.8692 (2) Å c = 7.4960 (9) Å V =538.8Å3 V =540.4Å3 V = 548.27 (3) Å3 V = 649.9 (1) Å3 density 3.10 g/cm3 3.11 g/cm3 3.09 g/cm3 6.96 g/cm3 optical properties (−) ω =1.658 (−) ω =1.654, (−) ω =1.664(3), (−) ω =2.017, ε =1.632, ε =1.650, ε =1.659(3), ε =1.999, Δ =0.006 Δ =0.004 Δ =0.005 Δ =0.018 strong lines and 1.852 (8), 1.729 (7), 1.766 (6), 2.839 (100), 2.739 (60), 2.655 2.858 (100), 2.771 (99), 2.988 (100), 4.32 (40), intensities in 1.463 (6), 1.904 (5), 1.819 (5), (45), 2.801 (44), 1.853 (43), 2.793 (90), 2.858 (41), 4.13 (40), 2.877 diffraction pattern, 1.792 (5), 1.486 (5) 3.462 (40), 1.484 (20) 3.435 (38), 1.851 (23) (40), 3.26 (30) dhkl and fluorine in ellestadite from Crestmore, this mineral is prepared from several fist-sized xenolith samples that were hydroxylellestadite (Rouse and Dunn 1982). Synthetic collected during fieldwork in Summer 2012. chlorellestadite was first reported by Pliego-Cuervo and The crystal morphology and mineral assemblage of the Glasser (1977). Later, chlorellestadite was described as an chlorellestadite were assessed using an Olympus BX51 opti- intermediate high-temperature phase in Portland clinker cal petrographic microscope, and a scanning electron micro- (Chen and Fang 1989; Saint-Jean and Hansen 2005)and scope – SEM Phenom XL (Faculty of Earth Sciences, was used as a synthetic phase for production of new techno- University of Silesia, Poland). Several locations suitable for logical materials (Fang et al. 2011, 2014). It merits noting that analysis in an electron-probe micro-analyzer – EPMA were Cl-bearing ellestadite was reported from burned coal spoil- selected from a number of polished sections. A mono- heaps near Brno, Czech Republic (Sejkora et al. 1999)but, mineralic chlorellestadite grain for single-crystal X-ray dif- to date, Cl-dominant ellestadite had not otherwise been found fraction was extracted from a polished section using a prepa- in natural rocks. ration needle. Recent study of Cl-bearing minerals in altered xenoliths The chemical composition of the chlorellestadite was de- from the Shadil-Khokh volcano revealed a Cl-dominant mem- termined using a CAMECA SX100 equipped with one EDS ber of the ellestadite group. This phase was investigated and detector and five WDS detectors with LIF, PET and TAP the new mineral species chlorellestadite (IMA2017–013) was crystals located at the Institute of Geochemistry, Mineralogy approved by the IMA Commission for New Minerals, and Petrology, University of Warsaw, Poland. The EPMA Nomenclature and Classification – CNMNC in 2017. instrument was operated at ~3·10−6 Torr, 15 kV acceleration The altered xenolith in which chlorellestadite was found is voltage, 10 nA beam current (measured with a Faraday cup) a pyrometamorphic rock formed under sanidinite facies and 5–8 μm diameter as confirmed by the beam imprint on the (larnite sub-facies) conditions at temperature above 750 °C specimen. The beam was intentionally defocused to reduce and low, near-ambient pressure. A metasomatic alteration of migration of, in particular, Na, F, and Cl (see e.g., Le Roy primary silicate-carbonate xenolith affected by fluid and gas and Roinel 1983; Morgan and London 1996). The instrument of volcanic origin, and enriched with chlorine, is responsible was internally calibrated against the following mineral stan- for the formation of chlorellestadite. dards: wollastonite – Ca, Si; baryte – S; fluorapatite – P, F; The type material of chlorellestadite is deposited in the albite – Na; tugtupite – Cl, and all elements were measured on mineralogical collection of the Fersman Mineralogical their Kα lines. Contents of other elements are lower detection Museum, Leninskiy pr., 18/k2, 115,162 Moscow, Russia, un- limits. Raw data were ZAF-corrected using the PAP-protocol der catalogue number 4975/1. (Pouchou and Pichoir 1985), and element contents were con- verted to oxides assuming stoichiometry. Main oxide contents in wt% were recalculated into atoms per formula unit based on Methods of investigation 8 cations and 12O (Table 2). Single-crystal X-ray diffraction on an extracted Chlorellestadite was initially identified as an unknown miner- chlorellestadite grain approximately 20 × 20 × 20 μminsize al by electron scanning microscope on polished sections was carried out using a SuperNova Dual diffractometer with a Chlorellestadite, Ca5(SiO4)1.5(SO4)1.5Cl, a new ellestadite-... Table 2 Chemical composition of chlorellestadite (mean 11) Table 3 Parameters for X-ray data collection and structure refinement for chlorellestadite Wt.% Range Stand. Dev. Temperature, K 293(2) CaO 54.43 54.71–57.51 0.37 Crystal data Na2O 0.07 0.00–0.18 0.05 Crystal system hexagonal SO3 22.72 22.90–23.70 0.22 Unit cell dimensions (Å) a = 9.6002(2) SiO2 17.67 17.64–18.95 0.19 b = 9.6002(2) P O 0.44 0.10–0.99 0.03 2 5 c = 6.8692(2) Cl 4.23 4.03–4.89 0.18 α, β =90°γ =120° – F 0.40 0.10 0.70 0.16 Space group P63/m (no.176) OH* 0.49 0.38–0.74 Vo lu me (Å 3) 548.27(3) 100.45 Z2 -O = (F, Cl) 1.12 Density (calculated) 3.148 g/cm3 99.33 Chemical formula Ca10[(SiO4)3(SO4)3]Cl1.56- *- water was calculated on the basis of charge balance F0.34 Crystal size (mm) 20×20×20 μm mirror monochromator (MoKα, λ =0.71073Å)andanAtlas Diffractometer super nova CCD detector (Agilent Technologies), located at the Institute of X-ray radiation MoKα/0.71073 Å Physics, University of Silesia, Poland.
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    Periclase MgO c 2001-2005 Mineral Data Publishing, version 1 Crystal Data: Cubic. Point Group: 4/m 32/m. As small octahedra, less commonly cubo-octahedra or dodecahedra, may be clustered; granular, massive. Physical Properties: Cleavage: {001}, perfect; on {111}, good; may exhibit parting on {011}. Hardness = 5.5 D(meas.) = 3.56–3.68 D(calc.) = 3.58 Slightly soluble in H2O when powdered, to give an alkaline reaction. Optical Properties: Transparent. Color: Colorless, grayish white, yellow, brownish yellow; may be green or black with inclusions; colorless in transmitted light. Streak: White. Luster: Vitreous. Optical Class: Isotropic. n = 1.735–1.745 Cell Data: Space Group: Fm3m. a = 4.203–4.212 Z = 4 X-ray Powder Pattern: Synthetic. 2.106 (100), 1.489 (52), 0.9419 (17), 0.8600 (15), 1.216 (12), 2.431 (10), 1.0533 (5) Chemistry: (1) FeO 5.97 MgO 93.86 Total 99.83 (1) Monte Somma, Italy. Mineral Group: Periclase group. Occurrence: A product of the high-temperature metamorphism of magnesian limestones and dolostone. Association: Forsterite, magnesite (Monte Somma, Italy); brucite, hydromagnesite, ellestadite (Crestmore quarry, California, USA); fluorellestadite, lime, periclase, magnesioferrite, hematite, srebrodolskite, anhydrite (Kopeysk, Russia). Distribution: On Monte Somma, Campania, Italy. At Predazzo, Tirol, Austria. From Carlingford, Co. Louth, Ireland. At Broadford, Isle of Skye, and Camas M`or,Isle of Muck, Scotland. From Le´on,Spain. At the Bellerberg volcano, two km north of Mayen, Eifel district, Germany. From Nordmark and L˚angban, V¨armland,Sweden. In mines around Kopeysk, Chelyabinsk coal basin, Southern Ural Mountains, Russia. In the USA, at the Crestmore quarry, Riverside Co., California; from Tombstone, Cochise Co., Arizona; in the Gabbs mine, Gabbs district, Nye Co., Nevada.
  • Light Rare Earth Element Redistribution During Hydrothermal Alteration at the Okorusu Carbonatite Complex, Namibia

    Light Rare Earth Element Redistribution During Hydrothermal Alteration at the Okorusu Carbonatite Complex, Namibia

    Mineralogical Magazine (2020), 84,49–64 doi:10.1180/mgm.2019.54 Article Light rare earth element redistribution during hydrothermal alteration at the Okorusu carbonatite complex, Namibia Delia Cangelosi1* , Sam Broom-Fendley2, David Banks1, Daniel Morgan1 and Bruce Yardley1 1School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK; and 2Camborne School of Mines, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK Abstract The Cretaceous Okorusu carbonatite, Namibia, includes diopside-bearing and pegmatitic calcite carbonatites, both exhibiting hydrother- mally altered mineral assemblages. In unaltered carbonatite, Sr, Ba and rare earth elements (REE) are hosted principally by calcite and fluorapatite. However, in hydrothermally altered carbonatites, small (<50 µm) parisite-(Ce) grains are the dominant REE host, while Ba and Sr are hosted in baryte, celestine, strontianite and witherite. Hydrothermal calcite has a much lower trace-element content than the original, magmatic calcite. Regardless of the low REE contents of the hydrothermal calcite, the REE patterns are similar to those of par- isite-(Ce), magmatic minerals and mafic rocks associated with the carbonatites. These similarities suggest that hydrothermal alteration remobilised REE from magmatic minerals, predominantly calcite, without significant fractionation or addition from an external source. Barium and Sr released during alteration were mainly reprecipitated as sulfates. The breakdown of magmatic pyrite into iron hydroxide is inferred to be the main source of sulfate. The behaviour of sulfur suggests that the hydrothermal fluid was somewhat oxidising and it may have been part of a geothermal circulation system. Late hydrothermal massive fluorite replaced the calcite carbonatites at Okorusu and resulted in extensive chemical change, suggesting continued magmatic contributions to the fluid system.
  • Introduction to Apatites

    Introduction to Apatites

    Chapter 1 Introduction to Apatites Petr Ptáček Additional information is available at the end of the chapter http://dx.doi.org/10.5772/62208 Abstract Apatite is the generic name, which was first introduced by German geologist A.G. Werner. These minerals and their synthetic analogs represent a major class of ionic compounds and the most common crystalline form of calcium phosphates, which are of interest of many industrial branches and scientific disciplines. Since, apatite (fluora‐ patite) is the most abundant phosphate mineral, apatite bearing phosphate rocks represents an important source of inorganic phosphorus. First chapter of this book introduces the basic concepts of nomenclature, composition, classification, crystal structure, mineralogy and properties of minerals from the supergroup of apatite. Furthermore, the minerals from the group of apatite and polysomatic apatites are described. Since, the most of the topics mentioned in this chapter will be developed in the following chapters, the key concepts provided in this chapter are important to understood before proceeding further. Keywords: Apatite, Group of Apatite, Polysomatic Apatites, Fluorapatite, Hydroxyla‐ patite, Chlorapatite, Vanadinite The minerals1 [1],[2],[3],[4],[5] from the apatite group2 [6] are classified as hexagonal or pseudo‐ hexagonal monoclinic anhydrous phosphates containing hydroxyl or halogen of the generic formula3: 1Minerals are individual components comprising rocks formed by geological processes classified according to their crystal structure and chemical composition. The total number of minerals accepted by mineralogical community is about 4000. Mineraloids are mineral-like phases including synthetic materials, human-treated substances, and some biological materials, which do not fulfill the criteria for the definition of mineral species [2].